On Wed, 16 Jan 2008 09:36:07 -0800 (PST), "
wrote:

But... the leg pump in the shotgun formation was created due of the
fact that the guys on the field literally cannot hear the snap count.
In the shotgun where they are a few feet away, I think most
quarterbacks have complained that when playing on another's home turf
they cannot hear anything. So think about the center, literally
pointed the other way trying to pick up the count...

It's also used (when not in the shotgun) to put the tight end in
motion.

Mike O.